1. Field of the Invention
The present invention relates to a honeycomb structure onto which a catalyst for purification of an exhaust gas is loaded, a honeycomb catalyst body using this honeycomb structure, and a manufacturing method of a honeycomb structure.
2. Description of Related Art
An exhaust gas discharged from an internal combustion engine such as an engine for a car includes harmful substances such as carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxides (NOx). When such harmful substances are decreased and the exhaust gas is purified, a catalyst reaction is broadly used. In this catalyst reaction, it is possible to realize generation of a harmless substance from a harmful substance such as carbon monoxide (CO) by simple means for bringing the exhaust gas into contact with a catalyst. Therefore, in the car or the like, the exhaust gas is usually purified by disposing the catalyst in the middle of an exhaust system of the exhaust gas from the engine.
To dispose the catalyst in the exhaust system of the car or the like, a honeycomb catalyst body is used in which the catalyst is loaded onto a honeycomb structure. In the honeycomb catalyst body, the honeycomb structure is formed by partition walls onto which the catalyst is loaded, and cells surrounded with the partition walls function as through channels of the exhaust gas. In such a honeycomb catalyst body, the exhaust gas is divided into small portions to flow into the plurality of cells, and in each cell, the divided small portion of the exhaust gas is brought into contact with the catalyst loaded onto the surface of the partition wall. Consequently, in the honeycomb catalyst body, by simultaneously treating the plurality of divided small portions of the exhaust gas, the exhaust gas can be treated with a high purification efficiency.
Furthermore, for the honeycomb catalyst body, a technology has been suggested in which a honeycomb structure is formed by porous partition walls having numerous pores, and a catalyst is also loaded onto inner wall surfaces of the pores of the partition walls (e.g., Patent Document 1). In this technology, the catalyst is loaded onto the inner wall surfaces of the pores to increase an amount of the catalyst to be loaded onto the honeycomb catalyst body. Furthermore, in this technology, an exhaust gas is allowed to flow into the pores of the partition walls to bring the exhaust gas into contact with the catalyst also in the pores, thereby further increasing a contact frequency between the exhaust gas and the catalyst.